1. Field of the Invention
The present invention relates to a die including a slide cam.
2. Description of Related Art
In the ordinary die, a lower die and an upper die are mounted respectively on a bed and a ram of a pressing machine so that piercing and forming processings can be accomplished by ascending and descending the upper die. Since the upper die is moved up and down, the transverse machining is effected by converting the vertical machining force to a horizontal machining force by using a cam member.
This will be explained by the example of piercing the side wall of the work with the die including the cam member.
As shown in FIG. 5 and FIG. 6, a positioning member 104 which positions the work 103 on a base plate 102 is scured to the lower die 101. At a position opposing a hole 105 to be pierced in the side wall of the work 103, a driven cam 107 including a punch 106 is slidably disposed. A heel 108 is secued to the rear side of the driven cam 107. A coil spring 109 is installed around the top side of the rod 110 which is threaded into the driven cam 107 inserted through the heel 108, and one end of the coil spring 109 is contacted with the heel 108, and a nut 112 is screwed onto the other end of the coil spring 109 via a washer 111 to urge such that the driven cam 107 is drawn back after piercing the work 103. A driving cam 118 is secured to a base plate 117 of the upper die 116 at a position opposing the driven cam 107.
When the upper die 116 is descended, the driving cam 118 moves the driven cam 107 forward against the biasing force of the coil spring 109 to pierce the hole 105 in the work 103 by the punch 106 and a die 125, and when the upper die 116 is ascended, the driven cam 107 is moved rearward by the biasing force of the coil spring 109.
For piercing the side wall of the work 105, as aforementioned, the driven cam 107 inculuding a punch 106 slides on the base plate 102 while approaching to and parting from the work 104. The driving cam 107 has to slide accurately to pierce by the punch 106 and die 125, therefore, flanges 121 are projected on lower opposite sides of the driven cam 107, and side guide plates 122 and upper guide plates 123 for guiding the flanges 121 are fixed to the base plate 102.
In the aforementioned die, in order to allow the driving cam 107 to slide between predetermined positions, the side guide plates 122 for guiding the side faces of the flanges 121 projected on the sides of the driven cam body 107a, and the upper guide plates 123 for guiding the upper faces of the flanges 121 are disposed. Since these flanges 121, side guide plates 122 and upper guide plates on 123 are provided, a length l is projected respectively on opposite sides of the body portion 107a of the driven cam 107, the length l being usually about 100 to 150 mm at a minimum, whereby a large space is occupied on the base plate 102 of the lower die 101 of the press die.
Accordingly, a large space is occupied when a cam mechanism is provided on the die. Since the large space is occupied by providing the cam mechanism, the die size is restricted by the bed area of the pressing machine and the necessary members may not be installed on the die, therefore, sometimes the machining processes must be increased and the die has to be added.
A wear plate 124 provided on the tip of the flange 121 projected on the side of the body portion 107a of the driven cam 107 wears as the driven cam 107 repeats the sliding operations, producing a gap between the side guide plates 122, whereby the driven cam 107 cannot slide linearly and tends to meander by the existence of the gap. The punch 106 installed on the driven cam 107 also moves similarly in a serpentine fashion, thus the punch 106 is unable to punch in the state wherein a proper clearance is maintained circularly around the die 125, producing burrs around the punched hole, thus a high quality punching is impossible. Besides, due to the punching by the punch 106 and die 125 which produce the burrs, edges of the punch 106 and die 125 become damaged.